Solar physicists solve the case of the missing sunspots

Nasa and the Indian Department of Science have solved a solar mystery that has flummoxed physicists: why did
the Sun lose its sunspots for over a year between 2008 and 2009,
resulting in a 100-year low for solar activity?

Sunspots are visibly-dark blemishes on the Sun's surface,
caused by raging fares of magnetic activity. Those intense bursts
of activity cause solar flares and coronal mass ejections, which
can play havoc with technology and communications back on
Earth.

The Sun sees a routine flow in the number of sunspots in
decade-long cycles. But as Solar Cycle 23 came to its end, around
2008, the Sun plunged into a year-long "solar minimum", with a
curiously low frequency of sunspots and solar storms. Solar Cycle 24 started back up in
2009.

It was the longest period of decreased solar activity for
almost 100 years, and it has baffled astronomers ever
since.

To understand the phenomenon, a team of researchers at
India's Department of Science and Technology -- with funding from
Nasa's "Living With a Star" Programme -- developed computer
simulations of the Sun's magnetic field to see how fluctuations in the star's inner
workings would affect the production of sunspots.

The computer simulation varied the speed and flow of the
Sun's plasma currents -- in the north-to-south, or meridional
circulation -- to simulate hundreds of different sunspot cycles.
The researchers found that a fast, violent flare of solar max in
the first half of the solar cycle and a longer, slower meridional
flow in the second half lead to a lengthy period of low sunspot
activity.

"Understanding and predicting solar minimum is something
we've never been able to do before -- and it turns out to be very
important," said Lika Guhathakurta of NASA's Heliophysics Division
in Washington, DC. As astronomers perfect their simulations, we will able to use this
information to better predict solar and space weather, long before
events like damaging solar flares take place.

So will astronauts, hundreds of years in the future, be
manipulating the Sun to cause artificial periods of extended solar
minimum? Well, while a long period of solar minimum sounds good, it
can also have some rather nasty repercussions.

Dangerous cosmic rays, which are normally held at bay by the
sun's magnetism, were free to seep out into the solar system and
threaten the safety of space travellers. Plus, the scorching UV
rays that usually cause space debris to decay, were absent. During the solar minimum,
"ironically, space became a more dangerous place to travel," Nasa's
Tony Phillips says.

Edited by Duncan Geere

Comments

Place me in the "Skeptical" cohort.I've been following "The Sunspots" since the beginning of Cycle 24.At that time the speed up of the belt was confidently predicted to INCREASE sunspots.NASA reported in 2006 that:"According to theory and observation, the speed of the belt foretells the intensity of sunspot activity ~20 years in the future. A slow belt means lower solar activity; a fast belt means stronger activity. The reasons for this are explained in the Science@NASA story Solar Storm Warning."http://science.nasa.gov/science-news/science-at-nasa/2006/10may_longrange/So they got the belt speed now bracketed ... Fast or Slow means more sunspotsI'll put this on my calendar to check after Cycle 25.Perhaps they'll have the "just right" speed theory ... or something else new.